Abstract

Most frequency-domain nonlinear-optical techniques measure only the magnitude of the Fourier transform of a temporal response and, hence, do not uniquely determine the response. We show that, for the commonly used response, h(t) = A exp(−t/τf) + B exp(−t/τs), where A ≡ α/τf and B ≡ (1 − α)/τs, the spectral line shape can always be fitted by two different values of α. A measurement of the optical Kerr transient of carbon disulfide illustrates this ambiguity. We also demonstrate a single-scan method that is free from such ambiguities. It involves adding coherent background with a nonzero quadrature-phase component, obtained simply by proper choice of probe wavelength.

Ironically, the two frequency-domain methods 3,5 that do involve coherent background contain in-phase, but not quadrature, background.

The existence of this ambiguity and its removal by the addition of quadrature-phase coherent background can also be seen when using Blaschke products.7 Ambiguity removal also follows from the observation that the Fourier-transform magnitude of a real decay is even, and adding iγ breaks this symmetry.

In the course of this work, the fit to the data of this experiment was slightly improved, yielding the parameter values reported herein.

Trans. Am. Math. Soc.

Other

Ironically, the two frequency-domain methods 3,5 that do involve coherent background contain in-phase, but not quadrature, background.

The existence of this ambiguity and its removal by the addition of quadrature-phase coherent background can also be seen when using Blaschke products.7 Ambiguity removal also follows from the observation that the Fourier-transform magnitude of a real decay is even, and adding iγ breaks this symmetry.

In the course of this work, the fit to the data of this experiment was slightly improved, yielding the parameter values reported herein.

Cited By

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.